According to Symantec, WannaCry encrypts data files and ask users to pay a US$300 ransom in bitcoins. The ransom note indicates that the payment amount will be doubled after three days. If payment is not made after seven days, the encrypted files will be deleted.

WannaCry has the ability to spread itself within corporate networks, without user interaction, by exploiting a known vulnerability in Microsoft Windows, says Symantec. Computers which do not have the latest Windows security updates applied are at risk of infection.

Symantec does not recommend paying the ransom. Encrypted files should be restored from back-ups where possible, it states.

In a blog post, Symantec shares the following best practices for protecting against ransomware:

New ransomware variants appear on a regular basis. Always keep your security software up to date to protect yourself against them.

Keep your operating system and other software updated. Software updates will frequently include patches for newly discovered security vulnerabilities that could be exploited by ransomware attackers.

Email is one of the main infection methods. Be wary of unexpected emails especially if they contain links and/or attachments.

Be extremely wary of any Microsoft Office email attachment that advises you to enable macros to view its content. Unless you are absolutely sure that this is a genuine email from a trusted source, do not enable macros and instead immediately delete the email.

Backing up important data is the single most effective way of combating ransomware infection. Attackers have leverage over their victims by encrypting valuable files and leaving them inaccessible. If the victim has backup copies, they can restore their files once the infection has been cleaned up. However organisations should ensure that backups are appropriately protected or stored off-line so that attackers can’t delete them.

Using cloud services could help mitigate ransomware infection, since many retain previous versions of files, allowing you to ‘roll back’ to the unencrypted form.

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